Kangryong District borders the West (Yellow) Sea on an extension of North Korea that protrudes west beyond the northwest corner of South Korea. These western waters separating the neighboring nations are part of the DMZ. At high tide, the ocean meets the base of hills and dikes. At low tide wide expanses of mudflats are exposed.
In 1987, Dr. Pak documented about 40 Red-crowned Cranes wintering along the coast of Kangryong District. When the mudflats were exposed, the cranes fed on small aquatic animals they pulled from the mud. When the tides were high, the cranes moved inland to drink fresh water and perhaps to feed on waste grain in rice paddies. The human population was low and the cranes thrived.
Unfortunately, by the 1990s the crane numbers declined to about 10, and in recent years to half that number. Concomitant with this decline, massive reclamation of crane breeding habitat in northeast China was underway, and the human population in Kangryong District increased. In the 1990s,widespread food shortages in North Korea, forced tens of thousands of humans into western mudflats to find food where several hundred Red-crowned Cranes formerly wintered. As their numbers declined in North Korea, the crane population increased along the DMZ. Dr. Pak is confident that the local people did not kill the cranes but that disturbance was responsible for their decline. Red-crowned Cranes were officially protected as Natural Monuments in 1975, a designation that the individual birds are sheltered, but not necessarily their habitat.